1. Field of the Invention
The present invention relates to a shoe ribbing machine for driving tacks into the insole of a shoe at a predetermined spacing through a rib disposed over the edge of the insole. The insole is part of a shoe upper that is fitted over a last of the shoe ribbing machine, the last being supported by a last carrier. More particularly, the present invention relates to a shoe ribbing machine including a tack driving device for driving tacks one after another into the insole of a shoe supported on a last, a tack conveying device for conveying tacks to the tack driving device, and a tack separating device for feeding the conveying device with tacks one at a time.
2. Description of the Related Art
In shoe ribbing machines of the above-mentioned type, a ribbing projecting above the last and to form part of the shoe upper is positioned along the edge of the insole by a screw, a peripheral band or inserters and is then fastened in place with tacks. Up to now, the driving-in of the tack by a tacking head of a tack driving device was controlled to move along the edge of the shoe upper in such a manner so as to drive tacks through the ribbing at predetermined time intervals. The beginning and ending of the tack driving-in process as well as the above predetermined time intervals from tack to tack can be set on the machine control of the shoe ribbing machine.
During the tack driving-in process, a supply of tacks accommodated in, for example, a magazine are separated into individual tacks, and the individual tacks are fed by a tack conveying device to the tack driving device. The tack conveying device has a tube or hose connected to the tack driving device and tacks are generally forced through the tube or hose by compressed air. The tack driving device is moved over the ribbing by, for example, a hydraulically or pneumatically driven cylinder. The speed at which the tack driving device is moved can be adjusted to be faster or slower by adjustment of the pressure or temperature of the operating medium of the cylinder. Since the operation of the tack separating device, the tack conveying device and the tack driving-in device, as well as the distance between successively driven tacks is based on time intervals set by the machine control of the shoe ribbing machine, the conventional shoe ribbing machine presents a significant drawback in that such time intervals are not constantly adjusted to correspond to the speed at which the tack driving device is moved. Accordingly, the distances between successively driven tacks are shorter along the ribbing when the tack driving device is moved slower than when it is moved faster.